Conserved cis-elements bind a protein complex that regulates Drosophila, ras2/rop bidirectional expression

• Published in: British journal of cancer Vol. 69; no. 2; pp. 264 - 273
• Main Authors: LIGHTFOOT, K, MALTBY, L, DUARTE, R, VEALE, R, SEGEV, O
• Format: Journal Article
• Language: English
• Published: Basingstoke Nature Publishing Group 01.02.1994
• Subjects: Animals; Base Sequence; Biological and medical sciences; Classical genetics, quantitative genetics, hybrids; Conserved Sequence - genetics; DNA-Binding Proteins - genetics; DNA-Binding Proteins - physiology; Drosophila; Drosophila - genetics; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation - genetics; Genes, ras - genetics; Genetics of eukaryotes. Biological and molecular evolution; Invertebrata; Molecular Sequence Data; Promoter Regions, Genetic - physiology; Transcription, Genetic; Binding; Insecta; Drosophila; Gene expression; Drosophilidae; Promoter; Proteins; Regulation(control); Arthropoda; C-Onc gene; Invertebrata; Diptera; Protooncogene
• ISSN: 0007-0920; 1532-1827
• DOI: 10.1038/bjc.1994.50

The Drosophila ras2 promoter region exhibits bidirectional activity, as has been demonstrated for the human c-Ha-ras1 and the mouse c-Ki-ras. Here we address a unique case of ras regulation, as Drosophila ras2 provides the only example to date in which the flanking gene (rop) and its product have been isolated. A linking mechanism of control suggests a mutual interaction between the two gene products. Our studies indicate that the Drosophila ras2 promoter region shares with the human c-Ha-ras1 promoter a CACCC box and an AP-1-like sequence. A 14 bp promoter fragment which holds a CACCC element is demonstrated to interact with a specific transcription factor (factor B). This CACCC promoter element represents a stretch of imperfect palindrome. We present evidence that this factor can form a complex with another specific DNA-binding protein (factor A). The binding sites (A + B) for these protein factors are essential for 95% expression of both genes flanking the promoter (ras2 and rop). Region A consists of four overlapping consensus sequences: a TATA-like element, a DSE-like motif (the core sequence of the serum response element), a DRE octamer, which has been shown to play a role in cell proliferation, and a 5 bp direct repeat representing the GATA consensus sequence. Factor A has a very weak affinity to the full promoter region, but when complexed with factor B binding efficiency is enhanced. We also show that alterations of DNA-protein binding specificities can be achieved by supplementing the growth media with different sera.